ReCodeTale
by Changeling with a Pen
Summary: Not everyone made it out of the Underground after Asriel brought down the Barrier...When the Void starts spilling into the empty Underground, bringing with it the mysterious WD Gaster and giving rise to half-coded amalgamations of our favorite characters, including a new being, Sans and Frisk must find a way back to the Surface whole. And what does Flowey have to do with all this?
1. Chapter 1: Return

Sans rocked back on his heel bones, staring down into the hole that Frisk had fallen into the Underground through with disdain, his trademark grin tense and uncomfortable. One of the first things he'd learned about the Surface was that there were no Resets here. No Save points, no timeline jumping, no do overs. He'd been filled with the most profound sense of relief upon this realization, feeling finally free of the constant fear of the Resets that had plagued him in the Underground. Which was why he was so disturbed now. If there was no more Save and Reset options, then why was there still an active anomaly in the timelines? He hardly needed to look at the reports to notice this one. It came with a queer twisting feeling in his soul. It made his bones feel hallow and kept him from sleep more often than not. He couldn't describe why exactly he felt so unnerved, only that he did.

That's why he'd volunteered to join the team of human scientists, and Alphys, that were planning an expedition to study the Underground, now that the barrier was destroyed and the way was open into and out of the mountain freely. It'd come as quite the shock to everyone, especially Papyrus, that the infamous lazybones would willingly volunteer to work. Sans had laughed, passing his decision off by saying that someone had to go and watch out for Frisk who, as monsterkind's human ambassador, was obligated to go as well. After that, it had taken a good three hours to convince him and Undyne that no, they didn't need to come as well. It took a very pointed blue-eyed glare to Undyne when Papyrus wasn't looking to finally get her to settle on the matter, too.

Frisk knew better, of course. They remembered the Resets, they felt that something was wrong. They knew what had been left behind down there.

They didn't comment on his expression, glaring down on the entrance to the Underground. They understood, better than probably anyone else, how many bad memories were buried deep in the mountain. Though it had led them to a new family and a happy ending once all was said and done, this hole had still been the starting point for a journey that had killed them countless times. They were scarcely any more eager than he was to jump back down.

"Hey! Are you two ready to go?" Kaila, the expedition leader, called to them from where the rest of the team was gathered a few yards away, near the other side of the hole. Sans jolted, shaking himself a bit before shooting a wide grin over to the team.

"Who us? We were _bone_ ready, pal."

Frisk giggled as they took his hand and walked with him over to the others, double checking that their climbing gear was strapped on securely over their lab coats. A pale blue flush spread over Sans's cheek bones. He still wasn't used to...well, to how affectionate Frisk was. Not that he was complaining, of course. The kid was like family to him.

After an hour of slowly and carefully climbing down the hole into the Underground, Sans wished he'd just taken a shortcut. If it'd just been Frisk and Alphys with him, they'd be half way to Snowdin by now. But his shortcuts were a little far out there, even for monsters, and he didn't really want to advertise his abilities to the humans.

When their feet finally touched down on solid ground, there was a collective sigh of relief that swept through the group. Sans glanced around. Nothing looked out of sorts yet, but then again, they'd only just arrived. He cast a look over to Frisk. Their back was ramrod straight and their mouth was drawn into a tight line.

"Hey kid, are you-" he started, only for Kaila to interrupt him with a loud clap.

"Alright everyone! We've got a lot to do and a very tight schedule to get it all done in, so let's get started. Max, take a soil sample from here. Yareli, you get that camera set up and take stills and full spectrum photos as we go along. I want this place fully documented."

Alphys shifted on her feet, her claws carelessly picking at the sleeve of her lab coat. " A-as far as the Ruins go, I'm n-not very familiar with them. Fr-frisk is the only one with us right n-now that's been through them. Should they lead a few of us on ahead to m-make sure everything is clear?"

Kaila nodded and looked to Frisk with a raised eyebrow. Smiling, they gestured to Sans. "There are some puzzles I remember up ahead. Sans and I will go make sure it's safe for everyone to come along," they said.

Kaila frowned and crossed her arms. "Just the two of you?"

Sans shrugged and threw an arm over Frisk's shoulders. "Sure, why not? I'll keep the kid outta trouble."

The head scientist eyed them warily, but ultimately waved them off and turned to talk to Alphys. As soon as no one was looking, Frisk seized his hand tightly and began pulling him down the path through the Ruins. Their fingers were trembling, making Sans's bones rattle against each other. Once they were far enough down the corridor that the rest of the team wouldn't be able to see them, Frisk's grip tightened even more and they started to run down the path.

"H-hey kid, what's the hurry?" He asked, tripping over his slippers to keep up.

Frisk's breath was coming in short, quick gasps through their teeth and their eyes were glued forward. "Something's wrong," they hissed, yanking him forward, urging him to go faster. Sighing, he jumped forward and pulled the human against him.

"Shortcut," he explained before ripping them through space.

They landed hard in a bed of soft, decaying golden flowers. The smell was so strong that Frisk gagged beside him (of course, that could have POSSIBLY had something to do with the teleporting, too). Sans looked at his hands and groaned. His bones were covered in the sticky decay of the buttercups.

"Huh, all the flowers are dead. We better get to the _root_ of the problem, huh pal?" He joked, looking up at Frisk for a reaction. He froze when he saw their expression though. Frisk was staring with hide horrified eyes at the flowers around them, holding a few rotted petals in their hands. They were shaking violently now, and their breathing was ragged and uneven.

"This is wrong. They should be alive. Something is horribly wrong," they insisted.

Sans tilted his skull at them and cautiously took ahold of their arm, trying to calm them down. "Hey, hey buddy. They're just some dead flowers. That's not too unusual. Doesn't mean the world is ending."

Frisk shook their head, grabbing onto Sans's hoodie sleeve like their soul depended on it. "Not these flowers, Sans. These are Asriel's flowers. Something's not right. You feel it too, right? I know you do."

The white lights that served as pupils faded from Sans's eyes as he looked away and chuckled without humor. He stood without answering, offering a hand to help Frisk up, which they accepted, still shaking slightly.

"We both know there's been something going on down here since everyone left," they murmured, brushing the last of the dead flower petals from their hands.

Sans was about to, reluctantly, agree, but something caught his eye at the corner of the cavern. Th shadows there seemed to be twitching, convulsing around themselves. For a second, he could have swore he saw a line of red coding, too.

He looked to the kid, who just nodded, wide-eyed at him. They'd seen it too. "C'mon," he said, taking the human's hand in his own this time, "let's keep moving."

They got through most of the Ruins unmolested. The puzzles were simple, and most could even be turned off by the switches on the walls. Every couple of rooms or so, though, they'd notice more of those strange anomalies in the shadows, or on the walls. Like reality wasn't quite lined up with itself. More than that, there were somethings that just shouldn't have been there. Sans didn't point out the double shadows he caught sight of to Frisk. It'd just freak the kid out more.

There was one other thing that was off, too. The SAVE points were gone. That sort of made sense, Sans thought. With no immediate threat to the human's life, there wasn't much need for the SAVE stars to offer RESETS. He wanted to be relieved. He wasn't.

Once they reached Toriel's old home, Frisk suggested they go back for the others.

"Don't ya at least wanna have a look inside first?" Sans suggested.

It happened right as he was reaching for the doorknob: the whole house glitched. It was like static, with the whole top half of the house spasming on and off center rapidly for a couple seconds, with a horrible ripping sound, before it settle back to normal. Frisk stumbled wilding back from the door, pulling Sans with them.

"Shit," he swore, instinctively putting a hand out in front of him and the kid, ready to attack.

Frisk was clutching at the back of his hoodie, frowning at the house. "The only way out of the Ruins is through Toriel's house. What do we do with it like this?"

Sans started walking backwards, hand still slightly raised towards the house in suspicion. "Well," he mused, "whatever these anomalies are, they don't seem dangerous on their own. I figure we'll just have to bite the bullet and go through once we've got everyone together."

Frisk chewed their lip. "Don't you think we should test that theory before we lead them through?"

Sans squinted at them. "How?"

Without an explanation, Firsk ran over to the tree in front of the house, which was glitching a bit on one side, and tentatively reached to touch the anomaly. As soon as they did, the piercing tearing sound came from the glitch and the whole section of the tree spasmed out of space violently, before it settled completely and left the tree unmarred, with no mark to show the glitch had been there in the first place. Frisk sighed deeply in relief and drew their hand up to their chest, grateful they hadn't lost the limb in their little experiment.

"Alright," they said, "let's go."

Just before they rejoined the group, Frisk had asked Sans not to mention the glitches. They said they didn't know why, but they had a feeling that the others wouldn't notice, and that they shouldn't tell them. Sans knew better than to expect a clear explanation- neither of them really understood what was going on- but he trusted the kid's judgement. Turned out that was a good call. As they walked back through the rest of the Ruins, no more anomalies showed up. And, even as they worked their way through the rest of the Underground, they didn't see anymore of the strange glitches along the way. Still, the weird feeling coiled up inside of Sans was getting harder to ignore with each passing hour. And, despite how hard they were clearly trying to appear as if nothing was wrong, he could tell Frisk was feeling off, too.

Sans and Frisk mostly left the field work to the research team, opting to lead everyone through the puzzles and act more as guides than anything else. That gave them plenty of time to check each area for signs of more anomalies, or for any indication that Flowey might be around. The soulless flower had been disturbingly absent throughout this little excursion. They both knew that, if he was still around, he must have seen them by now. If that was the case, he was probably following them, too. But they hadn't seen any sign of him, or even sensed him nearby. Sans couldn't tell if that was a good or a bad thing, based on Frisk's reactions. They looked like he'd d felt everyday down here: like they were just waiting for everything to go to shit at any second.

On the third night back Underground everyone was camped in the old castle. The plan was to return to the Surface in the morning, so by the time they reached the research center (a good three hour drive away), it would be just about noon. The team was mostly set up in Asgore's old room and the room that had been labeled as under renovations. Alphys had opted to take the couch in the living room. Frisk had asked Sans to stay in Chara and Asriel's old room with them, and he'd agreed. The kid seemed even more on edge tonight, despite how close they were to the door that lead back to the Surface. He looked over at them, curled up facing away from him in Chara's old bed. He frowned, wondering if sleeping in the same bed that that demon child once had would give them nightmares.

As if reading his mind, Frisk chose that moment to roll over in bed and stare at him, clearly wide awake. Startled, his left eye lit with blue flame and they both hissed at the sudden light.

"Aw geez kid, you almost put me into cardiac a- _rest,_ " he complained, pushing his palm into his eye socket as the blue light faded.

"Sorry," they murmured into the bend of their elbow, still watching him. Slowly, as if afraid someone was listening in on them, they whispered across the room: "Did you see them, too?"

Frisks eyes were wide and afraid in the dark, straining to focus on him for some form of comfort. With a sigh, Sans pulled himself from the small bed and went to sit with the human. This was really starting to get to him. He wasn't used to seeing Frisk afraid. After all, this was the kid that had gotten through the Underground without hurting a fly, and then befriended and liberated an entire civilization. Not to mention how many times they'd been killed along the way. In all that time, he'd hardly seen the kid flinch in fear. They must be really bothered to be reacting like this.

They scooted back on the bed until they were pressed against the wall, and sat up. They wrapped their arms around their knees and slouched forward.

"You noticed them, right? The shadows are twitching again in here," they whispered.

Sans sighed. He'd noticed them, alright. The anomalies had returned , subtle and unnoticed in the shadows. He wouldn't even have seen them if he hadn't been looking. It was just a sort of shift in the darkness- a split second where everything would jolt sideways and the shades of black wouldn't quite fit together. None of the humans had noticed it, besides Frisk, and neither of them had mentioned it aloud until now.

"Yeah," he admitted, "I saw a couple strings of code once we got to the Core. Doesn't seem to be too bad. 'Sides, we'll be outta here again tomorrow." He tried to sound as optimistic as possible, even with his own feeling of dread building as the night went on.

Frisk chewed their lip. "The golden flowers are all wilted," they pointed out. " The others just thought it was neglect since everyone left, but I saw that it bothered Alphys as well. As far as we know, Asr...Flowey is still down here somewhere. Even if we haven't seen him. Could he have something to do with it?" They visibly flinched when they corrected themselves on the soulless flower's name, still having a hard time separating the murderous flower from the sweet monster prince he'd once been. But one of Asriel's last requests had been for them to not think of the flower as being him, so they tried.

Sans slouched back against the headboard of the bed and wrapped a comforting arm around Frisk's shoulders. He leaned his skull against the kids hair and closed his eyes. All this anxiety was tiring him out.

"There's nothing we can do, for now," he reasoned. "Let's get back to the Surface. If you want, maybe we can come back and check out the anomalies later. Just you and me. But maybe...maybe it'd be better to leave the Underground be, ya know? Let it decay, undisturbed and empty. It took a whole lot to get it that way, after all."

Frisk didn't respond, and Sans couldn't say for sure how long after that they both fell asleep propped up against each other. Sans dreamt of blackness and glitches, streams of red code, and skeletal hands with holes in them.

Sans snapped awake violently to the sound of someone rapping on the door. It was one of Kaila's research assistants, telling them it was time to get up and packed for the Surface. Relaxing, he sucked in a few shaky breaths through his teeth and looked around. Frisk had slip down through the night, ending up half curled under the hallow of his ribs. Stifling a chuckle, he gently shook their shoulder.

Frisk groaned and smothered their face into his hoodie. "Five more minutes," they grumbled. Grinning, Sans wrapped both his arms around them and hoisted them up as he stood, making them yelp and grab at his shoulders and ribs.

"Sans!" they shrieked, one arm waving frantically at the ground.

"What? Kai said it was time to _get up_ so..."

"Sans, no."

"Sans yes."

It took a little over an hour for everything to be checked and secured. Everyone regrouped in the throne room, with Alphys coming in last. She seemed a bit tweaked, like she hadn't slept all night, and Sans wondered if the whole thing with the flowers dying had kept her up. Frisk had stayed pretty close to him since they got up, though they managed to refrain from clinging to him in front of the other humans. They knew that, as an ambassador, they had to maintain an image of independence. Still, they shot Sans a concerned look after they caught sight of the dark shadows under Alphys's eyes. Sans nodded almost imperceptibly to them. They were almost home, he thought. It'd be fine once they got back. But those thoughts in his head came in Frisk's hopeful voice, and were barely covering up his own inner monologue. The one he'd tried to leave behind after their first weeks on the Surface. The voice that whispered that everything was pointless, that he was helpless and should be prepared for the worst, because that was all he'd ever get in the end. He clenched his jaw tight and tried to ignore the echoes of the traitorous thoughts in his skull. He was used to it. He had to be strong now for Frisk, no matter how nervous he felt.

The door that had once lead to the Barrier corridor now lead to a long path of black and white stairs, leading up and out onto the Surface, the walls turning to stone the higher up one climbed. Sans had only seen it once before, when everyone had climbed to freedom nearly a year ago. Now, he followed behind the humans and Alphys, who hung back slightly with he and Frisk. Frisk was holding his hand now. Almost crushing it, really. They'd started to tremble, wide eyes darting all over the walls of the corridor. Even Alphys was muttering to herself, fidgeting more than usual and nearly tripping over her own feet more than once.

They were more than three quarters of the way through the corridor before a feeling hit Sans like a ton of bricks, nearly bringing him to his knees. His bones felt like lead, and the space around them like jelly. He could barely move. Frantically, he squeezed Frisk's hand even tighter in his, refusing to let go not matter what was going to happen. He heard a choked sob come from Frisk, but he couldn't stop looking ahead. Alphys and everyone else had continued walking like nothing was wrong. He tried to call out to them, but no sound would come out. He heard Alphys keep muttering to herself, and caught a few stray words: "The flowers...no response...determination...decay...photon...negative."

The whole corridor glitched, space and time seizing sideways and down, cracking and screaming. Streams of red coding filled his vision, and all he could feel was Frisk's hand heavy in his. Then there was blackness.

"PHOTON READINGS NEGATIVE...WHAT DO YOU TWO THINK?"


	2. Chapter 2: Lab

Consciousness returned to Sans with a gentle but insistent tug on his soul, and the intrusive feeling of fingers on his ribs. His eyes snapped open and locked onto the culprit. Well, they tried to. An unclear figure hovered above him, its entire form glitching out of focus like static. It didn't seem fully formed, and he couldn't make out any details, other than the free-floating black fingers that were curled around his rib with one "hand", and prodding at his soul with the other. Red lines of code danced aimlessly around the figure, and a sort of pitch-shifted humming was coming low and piercing from what appeared to be its head.

Everything happened in a split second, between Sans spotting the figure and it noticing his attention. As soon as it did, the glitches around it spasmed violently and furious lines of the coding wrapped around its form. The thing seemed to rise off him and wail a bit before disappearing altogether.

All at once able to move again, Sans jolted up and pressed his hand to his sternum, eye sockets wide. He found Frisk only a couple of feet away, only just starting to sit up and staring at him with an equally shaken expression. Relief swept through him like a tidal wave and he grabbed Frisk's wrist, dragging them into a bone-crushing hug. He heard them choke on a little sob, muffled in the folds of his hoodie, as they returned the embrace, clutching desperately at his back. He couldn't tell which one of them was shaking.

"Sans," they whimpered, "Sans, are you alright? What was that thing? What happened?"

Still holding onto Frisk, he took a moment to look around properly. They were back at the door that should lead back up to the Surface. But it was different. The door stood slightly ajar, its massive edges unstable and glitching sporadically, and through the opening all Sans could see was blackness. Not the normal darkness of shadow that usually obstructed the arched door, but...true, deep blackness that seemed to be sucking in the light around them. He even thought he heard a steady stream of white noise coming from the darkness, humming high at the fringes of his senses. The rest of the dark hallway seemed the same as usual, though. Still, he could feel in his bones that something had shifted. Whatever it was that had felt "off" when they'd first got back Underground had been pulled to the forefront, vivid and screaming at his senses as if it'd been held back by something before that had suddenly disappeared.

As for the...thing, that had been grabbing at him a moment ago. Well, to be honest, Sans had no guesses as to who or even what that had been. It didn't look like any monster he'd ever met. Not that he'd gotten a good look at it, of course. But not just any monster could prod at another monster's soul like that. It was certainly a cause for concern.

"I'm fine kid, I'm fine. And I don't know. Did it touch you? Are you ok?"

"No, I'm alright."

Pulling themselves up and dusting off, Frisk wiped the tears from their cheeks on the back of their sleeve. They cast a wary glance at the door to the Surface and took a few determined steps towards it, before thinking better of it and backing off.

"Sans, what do we do now? There has to be something we can do to get back to the Surface. Mom's going to be so worried..."

Sans flinched at the mention of Toriel. The kid was right. Having Frisk stuck down here with no way of knowing they were okay is the last thing she needed on top of the lingering trauma of the children she'd lost before. Knowing that Papyrus would be predictably very loudly hysterical wouldn't help either. . Scratching at the back of his skull, he waved towards the other end of the hallway.

"Only thing I can think of to do for now is go back the way we came. Maybe something's changed. Least we can do is get back to the Lab and see if we can get any readings on what these anomalies are."

Casting a last hesitant glance at the glitched out door that should have brought them home, Frisk nodded and started to head back down the hallway, chin stubbornly held up and shoulders back. Determined. Sans tried to hang onto a bit of their will, pushing forward.

Asgore's garden had been wilted the first time they'd passed through, but neither of them were prepared for what was left of it now. Dried and brittle stems littered the ground, not a single petal in sight. Dust blanketed the ground like fine snow, laying completely undisturbed by the anomalies that had almost completely consumed the throne in the center of the room. The throne seemed pixilated, the boxes of its mass shifting out of place, most of it having become crudely monochromatic while the rest was a sporadic mix of too-vibrant shades of yellow, red, and green. Entire sections seemed to be missing from the throne, too, with tiny sections of what almost looked like red coding hanging suspended where they should be.

Sans' eyes narrowed at the glitches, the lights that served as pupils growing dim, as he made a frustrated 'tsk'ing sound behind his teeth. He lead them both around the flowers, keeping them as far away from the walls as he could too (He could swear he saw them twitching a bit). He kept a protective hand around Frisk's wrist, nerves coiled tight in his bones.

They found the rest of New Home very much the same as the throne room. The long hallway where Frisk had found Sans waiting to judge them during their first journey had turned completely black and white, the light that cut between the glitching pillars sterile and harsh like florescents. In the house, there were massive chunks of space just.. missing, replaced by twitches of code and what looked like boxes of white pixels.

The first other person they met back along the way was a short, monochromatic little serpentine girl that reminded Frisk of Monster Kid. She was sitting at the bottom of the elevator from New Home, leading into the Core. Well, sitting wasn't quite the right word. They were slumped forward, looking lifeless, with wide, empty eyes. If not for the semi-regular rise and fall of their breathing, Frisk would have thought they were dead. Crouching down in front of the armless little monster, Frisk stooped at an awkward angle to look at their face.

"Hello? Are you alright?" Frisk raised a careful hand to their shoulder, giving the monster girl a little shake. She didn't react at all. She didn't even blink.

An uncomfortable feeling of haunting familiarity tugged at Sans's soul and he gently pried Frisk away from the motionless monster. Something scratched at the back of his mind, like the memory of a dream you can't quite remember. The feeling was too close to the confusion the Resets had caused at the beginning for his comfort, and he couldn't bring himself to look at the still figure any more.

"She's alive kiddo. Let her be. We've gotta keep moving."

They stood, still looking down with concern on the monster girl. "But Sans, we have to help her. We can't just leave her here like this." They tried to sound determined, but Sans could hear the agonized resignation in their voice. Frisk was a smart kid.

He shook his head, glancing at the motionless figure and back at Frisk. "Best we can do for her right now is figure out what's causing all of this. She'll be ok." He tried to believe his own words. Truth was, he had to find a way to get the kid and him back to the Surface, as far away from here as possible. They needed to get back to Papyrus and Toriel. To their family. He couldn't be stuck down here again. He wouldn't. Not like this.

Pulling Frisk along down the corridor, through the Core, neither they nor Sans saw the monster girl's head tilt towards them and watch them go before a mass of code and glitches coalesced on her and she was gone.

It would have been impossible to traverse the Core if it weren't for Sans's ability to teleport, with how much of the architecture had been erased by the anomalies, leaving gaping holes that fell into pits of lava. The elevators were out of commission, forcing them to traverse the complicated rooms of the whole Core. After the ninth jump, Frisk had to lean most of their weight on Sans to walk, their vision swimming and their soul quivering in their chest.

Sorry kid," Sans said, holding their elbow to steady them. They gave him a weak smile and pressed a hand to their sternum, trying to steady their breathing. They'd made it out of the Core, MTT resort within sight. From the outside, the Core looked even worse than it had inside. It was like the whole structure had rusted black and red and was twitching and melting into the lava beneath it. The structure seemed to be emitting a low groaning noise that echoed off the high roof of the Underground. They both shivered at the sound.

MTT resort had morphed, appropriately, in the most dramatic way imaginable. The whole thing had become blocky and monochrome, with a single wide line of the interior glitching into vivid neon colors that hurt to look at for too long. The Metaton-shaped fountain was still going, but it was spewing a thick black liquid that smelled of ozone instead of water. The door to the elevator had glitched out of existence, leaving only a patch of white pixels and long, thin lines of red coding behind. Frisk pulled away from him to peek into the Glamburger stand, which was part of the too-saturated strip of the resort, and leaned back out after a moment with a small frown.

After almost a year of monsters being on the Surface, they hadn't really expected there to be any food left around. Monster food didn't rot and expire like human food did, but it had mostly been hoarded and carried to the Surface once the Barrier had broken. As excited as everyone had been, they'd also been aware of how uncertain things would be above. Who knew where they'd get food from next?

Sans had never wanted anyone he cared about to face that uncertainty again. He could tell just by looking what was bothering Frisk. He tried not to worry. He knew where they could get food, if the anomalies hadn't messed with it, but at this point they were both traveling precarious territory and that stubborn, pessimistic voice in Sans's head was back in force. It didn't help that the queer, twisting feeling in his bones from before had just kept getting worse, joined now by the acute feeling of being watched. If the freak he'd woken up to crouched on top of him was any indication, then they were absolutely being watched. Still, some despondent part of him couldn't shake the idea that it was Flowey watching them from the shadows, planning some new scheme that would wind up snatching away everything he loved again. And this time, there wouldn't be any SAVE files to Load back to.

A bit of the floor started glitching too close to Sans's foot for comfort, and he scooted away from it with a frown. "Kid, I know that the jumps are rough on ya, but are you sure you we shouldn't just take a shortcut to the Lab? These anomalies are starting to freak me out."

Frisk shook their head. "We have to see if anyone else is here. Besides, with how messed up everything is, it isn't safe for you to keep teleporting. You can't take a shortcut if you don't know if your destination has been swallowed up by glitches, right?" They turned back from where they'd been looking into the old restaurant and stood at his side, glancing up for just a moment with a look of concern. "Not to mention the fact that you're exhausting yourself. I noticed. We can walk."

Sans grinned sheepishly at them. Damn, but the kid was way too sharp for their age. Weren't teenagers supposed to notice nothing but themselves? He guessed that a couple hundred resets and a few thousand times dying did something to you. God knows they'd taken their toll on him.

They didn't see anyone else on their way to the Lab, but it became evident that the further into the Underground they went, the worse the anomalies were. The unnerving wailing that the glitches emitted filled the air in a low drone that followed them everywhere. The scent of burt metal and ozone, and something over-sweet that was too much like dead flowers, hung about them, too. The anxious feeling inside Sans had become almost a physical ache, groaning coarsely in his soul. He could feel sweat beading on his skull, and the lights in his eyes were dim, darting around them restlessly. It was like danger had become a palpable thing, hanging like thick, choking fog in the air around them, setting their teeth on edge. Frisk was pretty obviously faring just a poorly as he was. They kept a hand clutched tightly to his sleeve as they walked, and Sans could feel that hand shaking ever so slightly. The kid had gone pale, and he even heard them muttering "determination" to themselves a couple of times. Their other hand was clasping the heart-shaped locket at their collar in a vice grip, turning their knuckles white as the bone beneath their skin.

On their first walk through, with the research team, Sans had noticed a few stay objects with double shadows. Now, it was like some objects had become shadows themselves, their vague shapes turned wavering black masses. This anomaly was relatively small, compared to the twitching, blocks of missing pixels, and lines of barely-there red code (which would get hazier the closer Sans tried to look at it). It only appeared here and there, swallowing up small objects that would hardly be noticeable, blending into the stark black and white that seemed to have spread through the Underground like an infection, if it weren't so damn bizarre. For a few minutes, though, it seemed like that particular glitch had thinned out completely. Until they reached the Lab, that is.

The entire Lab was a featureless mass of blackness and spasms of red code, sucking in the flat light around it and swaying more than twitching. Sans wondered if it was what a black hole might look like, if you could look into one. There was nothing to the Lab, now.

Except for the door, standing still and untouched by the anomalies, right where it should be.

And hell, if that didn't freak Sans out more than all the rest of it. This was so obviously a trap that he almost laughed, except that he knew they had to walk right into it anyways.

"Well, alright then," he sighed in resignation, taking the hand Frisk had tangled in his sleeve firmly in his own. Didn't matter one way or the other what ended up happening to them, he wasn't going to leave the kid on their own in this place.

Frisk chewed their lip for a minute, just staring at what had become of the Lab, before pulling him forward and pressing the release button on the door. It slid open slowly, creaking as if long since rusted. The whole building(?) gave a long, sharp keen as the door opened, revealing a dark, dusty room. But a room, nonetheless.

Frisk groped at the walls for some sort of light switch, but there was nothing. Sans looked around. The light mechanism should be on the far wall, if nothing had changed, but he couldn't see through the darkness to it. It was like the darkness was swirling through the air, a thick, soupy substance rather than the mere absence of light. He narrowed his eyes, blue light flickering to life in his left socket and bathing the room in a dim glow.

"I didn't realize you came with a built in flashlight, " Frisk teased, a weak smile on their lips.

Sans grinned, winking his glowing eye and plunging the room back into darkness for half a second. "Yeah, well, I'm a pretty _bright_ guy after all. Consider yourself en _light_ ened."

Frisk tried and failed to cover their giggles with a groan. Sans considered it a minor victory.

The Lab looked, to their surprise, widely undamaged. What hadn't been brought to the Surface sat untouched, covered in a fine layer of dust. The escalators had both stopped running shortly after Alphys had moved away, and the massive screen that had tracked Frisk's adventure a year ago was black.

Sans crossed the room and flipped on the light mechanism. Only about half of the lights came on, dim and flickering, but it was more than his eye had provided. He let the blue light fade and blinked a few times, taking a better look around. To his relief, the elevator down to the True Lab seemed in working order. Even if it wasn't powered, he could use his gravity magic to lower it down.

First, though, he pulled Frisk back over to the bare desk in the center of the room,pulling open drawers and rummaging through the things- mostly trash, really- that had been left behind. True to character, he found just what he was looking for. He pulled a chocolate bar from the back of the bottom drawer, his grin widening as he handed it to Frisk.

"Here ya go, buddy. That's a start. We can get some chisps down below, too."

"What about you?"

Sans shrugged. "I don't need it like you do. I'll get some chisps, too, and be fine."

Frisk pocketed the candy bar and smiled up at him, filled with determination.

The elevator door slid open for them without a qualm, and Sans figured he wouldn't have to use his magic after all. Still keeping a protective hand around Frisk's, he pressed the button for the bottom floor of the True Lab. The elevator hummed with electricity, jolting a bit before slowly descending.

Then there was a loud, sharp snap, and they were falling.


	3. Chapter 3: Remnant

**Author's Note: Oh golly, I am so sorry this took so long! I really have no excuses other than this chapter was really, really hard for me to write, and that I've been basically living at work. I have no intention of letting updates take this long often. Thank you so much to everyone reading this, and especially for those following, favoriting, and COMMENTING! Oh wow, thank so much, really! Well, here you go. I hope it was worth the wait.**

Contrary to popular belief, Sans was not, in fact, a fragile creature. It was true that he only had one HP point, which meant that in a fight it would only take a single direct hit to his Soul to kill him. But that was a fight, where his soul was taking all the damage. His body, on the other hand, could take quite a lot, actually. He was all thick, hard bones- much more so than a real skeleton by all means- and they'd seen their share of scuffs and scrapes. Which was why he wasn't altogether concerned for his own well being when instinct screamed at him and he grabbed Frisk's soul with his blue magic and tugged them sharply off the floor only a second or so before impact, leaving himself to take the crash full on.

He was thrown hard against the elevator wall, the sharp sound of bones cracking against metal ringing in his ears. He lost his hold on Frisk, and he could sense it when their soul turned red again and dropped them to the floor. His vision was swimming, spots of black clouding parts of his sight so completely that they could have been glitches themselves if he didn't know better. He watched with an airy detachment, head foggy with pain, as Frisk crumpled to the floor before scrambling to pull themselves up and over to him. Their hands fluttered wildly about his face, afraid to touch him.

"Sans! Sans, oh god, are you okay? Say something."

He blinked slowly, the hazy pinpricks of light in his eyes rolling up and to the side. He groaned, letting his skull loll back against the wall. "I'm goin' _tibia_ fine, kiddo. Just got a little rattled."  
Frisk didn't laugh, but they wrapped their thin little arms around his neck and stifled a frightened sob in the fur of his hood. He didn't let himself flinch at the shock of pain that ran through his left radius as he wrapped his arms around the kid's back and hugged them close, patting their head soothingly. He could see the thin, splintered line going lengthwise halfway down his arm bone where his sleeved rolled up against Frisk's back, and chose just to be grateful that that seemed to be the worst of it. A fracture was inconvenient, but would heal quick enough once he got some food. He didn't want to risk things like that on Frisk, though.

"C'mon. Let's go check things out," he said, giving them one last comforting squeeze. Frisk released their hold on him and sniffed, nodding as they wiped at their damp cheeks. They pushed themselves to their feet and Sans swayed a bit where he stood. Firsk eyed him with concern but he quickly righted himself and gave them a reassuring grin. He pressed his right hand against the elevator doors, still tightly shut, and tried to press his fingers into the space between the doors. They gave in to him easily, ad he was able to slip his whole hand into the space he created and pry the doors open with almost no effort.

He almost wished he hadn't.

The True Lab's first hall was dark, darker than usual, with only the grim red glow of the back up lights illuminating the space. What that left to be seen was the masses of convulsing black ichor that slid down the walls and pooled in lazily shifting puddles on the floor. The thick, dark liquid gleamed dully with the red lights, making it even eerier. Looking around, he noticed that the wall that the elevator was built into was almost completely covered by the stuff, and it was oozing steadily downwards towards them.

With a muffled curse, he pulled Frisk out and away from the elevator. The doors snapped shut the minute they were out, and the black liquid started to cover the door.

"Shit," Sans hissed through his teeth again, backing up until he and Frisk were in the center of the hall. He knew if he had to, he could teleport them both back up to the Lab. No, what bothered him was that they were so obviously being lead. The elevator was a trap. The whole damn Lab was a trap. Sans wasn't a big fan of being played. He'd had more than his share of being part of a game in his life.

A few feet to their right, black tar oozed around the edges of a message screen that showed static for a second before going dark. Unsure what else to do at this point, Sans carefully inched himself and Frisk over to the screen, unsurprised when it flickered to life and displayed a shaky message . The words sparatically switched fonts, going from Arial to an alphabet of strange, illegible symbols , and back again, forcing Sans to read the message over a few times before it really set.

" ENTRY NUMBER 1.

[100100100000111001110000101000101111H0W !NTEREST!NG. . 1001.. .1]

"What the hell," Sans muttered, eye sockets narrowing at the message board. He'd been assuming that Flowey, the only known person that had been left behind down here, was the one manipulating them. It wouldn't be the first time. But this was clearly not the soulless flower's doing. Flowey was many things. Cryptic wasn't one of them.

Frisk seemed to be thinking the same thing, worrying their lip between their teeth and gently urging him on to the next board.

It came to life as they approached, displaying a new message in the same wavering fonts.

"ENTRY NUMBER 2

10000001001!T'S GR0WN. .01. MALLEABLE. . .01011. PERHAPS . ! .0"

"ENTRY NUMBER 3

[!REDACTED!]"

"ENTRY NUMBER 4

[!REDACTED!]"

"ENTRY NUMBER 5

00000000000000000000000\. . .HELL0, CH!LDREN."

Frisk sucked in a sharp breath through their teeth and jerked Sans's cracked arm hard as they stumbled a few steps backwards. At any other time, the kid would have noticed the slight wince that he hadn't quite managed to suppress, but right now they were to busy casting wild, frightened glances all around them. The message board twitched, the font going sporadically from white to red, those last two words- so obviously directed at them- flashing into those illegible symbols for half a second.

Sans's skull throbbed. He recognized this feeling. It'd creep up on him every now and then, when he was fiddling with the machine in his lab, or sitting alone for too long in Waterfall. This white noise would echo around in his head, driving him nuts.

He heard a shuddering sigh escape at his side. Beyond the knee-jerk reaction of fear, Frisk had the strangest look of...was that relief on their face? Sans's eye sockets narrowed and he tilted his skull at them. "Expecting somethin' else, kid?" He paused, considering, then added, "I sure wasn't expecting...well, that, either."  
Frisk gave themselves a little shake before glancing at him, then nodding to the monitor. "Flowey, I guess. Or. . .maybe Chara." They barely whisper the name, haunted by the memory of Chara even as they're free of their ghost. The kid'd had that demon in their head long enough to recognize how they spoke. This wasn't it.

Well, there went their list of suspects. Sans' bones ached in silent warning. Maybe it really was better to deal with the devil you knew, rather than one you didn't.

Frisk kept a tight hold of Sans's hand as they made their way down the long, narrow isle that lead to the rest of the True Lab, taking care not to touch any of the thick black ooze that slid off the walls and onto the floor. When the space opened into the front room, the glitches were back. Not many, but some of the puddles of ichor are pixilated, with snatches of code floating through them. The elevator was ruined, its metal doors wrinkled inward like paper, black goo seeping through the cracks from the other side where it was dark, dark, dark. To the right was another display monitor, as unmolested as the others had been, and to the left was the vending machine, equally so (somehow?). Frisk didn't even hesitate to run up to the machine, shoving in coins and retrieving first one, then three more bags of popato chisps. They tore into one, handing him the other three. He are one, slower than his clearly ravenous human pal, and felt the crack in his arm mend. The other two he stuffed into his hoodie pockets for the kid to have later.

They went to investigate the new message when he felt Frisk's hand slip from his. The board didn't illuminate itself beyond flickers of black and white static, emitting a low whine, so Sans turned to check out whatever had drawn Frisk's attention.

And there it was. He understood how he'd missed it upon entering- it wasn't gold and bright like he'd expect, but a dark and ominous purple that seemed to suck the little light there was around it inward, swallowing it whole. The shape was sharp and clear, but the bottom point dripped slow, consistent drops of the black liquid around them. Still, there was no argument for what it was: a SAVE point. Sans felt sick, his eyes going black. He could hear the pitch of the whine from the board behind him shift and the light bent around him when the message finally appeared. It only made things worse.

"ENTRY NUMBER -

10.D0 TAKE CARE. 0.. .BETTER TO SAVE 0110 THAN TO D!E. 01.1.11"

Frisk was already kneeling in front of the corrupted SAVE, holding it against their chest with a pained expression. Sans could see the SAVE pulse in time with their soul, the darkness of it seeming to drink in some of the bright red determination inside them. Frisk shivered violently as they released the SAVE star, jumping up and staggering away from it with their eyes squeezed shut. Sans grabbed their elbow to steady them, the lights that served as pupils returning dim and concerned.

"Hey, you okay kid?" He asked, though it seemed like a stupid question. Frisk feels cold to the touch, and Sans glared at the SAVE star like it could see him. Hate for the little black star curled up in his ribcage, seething and hot and useless.

"I'm fine," they lied, standing on their own but keeping the fingers of one hand curled around his sleeve anyways. They walked over to the message board on shaky legs, but it's gone blank. It stayed that way until they were just an inch away from it, before flickering to dim life and displaying new words: " D0NE, CH!LD. 101!.00"

Sans couldn't describe the feeling that filled the room at that moment other than to say that the darkness seemed to smile at them, the way it seemed to grow darker, yet darker still and curve around them. Of course, nothing really moved but the constant roiling of the black tar.

He put a protective arm around Frisk and drew them back against him, edging away to the middle of the room, eye lights scanning every inch. He knew he wouldn't see anything, but he had to try. They were being watched, that was clear. The whine of the message board stuttered, and it sounded horribly like laughter to him.

Frisk tugged lightly on his hoodie to get his attention and said, "Let's keep going. There's nothing else to see in here."

They took the right path, eyes constantly finding the glitches and grime whenever they got too close. The door slid open for them without protest. The next display board they came upon had the same "[!REDACTED!]" message displayed, letters twitching into symbols. But the one after that had a single, clear sentence: " Y0UR STEPPP, CH!LDREN.011" Sans scowled at the sign, rolling the lights of his eyes.

When they came upon the room with all the beds, they froze. The entire floor beneath the beds had been overtaken by a massive pool of the ichor, and the beds where sinking into it, some of them almost entirely consumed already. The dog bowl was floating on top. They both groaned. Sans quickly wrapped Frisk in his arms and teleported them to the other side of the room. There, at the front of the room, was another message board, and another SAVE. Frisk stood in front of the SAVE, just staring down at it. The message board's static whined high and long, impatient. When Frisk still didn't touch the SAVE, a message flickered onto the board.

"111001 . .0. WELL? ? ? WHAT ARE Y0U WA!T!NG F0R, EXACTLLLLY?00" it read, somehow managing to convey irritation.

Frisk bit their lip and looked from the sign back to the SAVE. "I don't want to," they said. Sans bit out a sharp laugh. Kid had the right idea, he guessed. Still, talking to sentient message boards wasn't really something he'd expected out of the day. . .or, seemingly omnipresent beings using display boards to communicate.

The display crackled with static before reshaping itself into a new message. "10!00 THAT 1S UNDERSTANDABLE. .10001. .HOWEVER, !T !S FAR M000RE PER!L0US N0T T0.11001"

Frisk frowned. "Who are you?"

Of course, the message board keened and displayed a mocking "[!REDACTED!]"

Frisk narrowed their eyes at the board and crossed their arms over their chest, scoffing. The message scattered again and reformed into a placating "000000A FR!END. . .00000"

Then it was Sans's turn to bark out a short, disbelieving laugh, humorless and harsh. The darkness around them seemed to boil for a moment, and Sans got the distinct impression that it was heaving a long sigh. Though, the scratchy whine that the agitated glitches made hardly resembled any kind of sigh he'd ever heard.

The display went completely black and still for a long moment before, with no interference at all, an amendment appeared: "AN ALLY, THEN. AT PRESENT, THE ONLY ONE YOU HAVE."

Sans shrugged and looked to Frisk. "I dunno. What do you think, kid?"

Frisk chewed their lip and stared at the message for a moment, seeming to mull over their choices, before kneeling in front of the SAVE and, reluctantly, pulling it against their chest. Their eyes screwed up tight and a tremor shook their shoulders before they released the dark SAVE and sucked in a few shaky, panting breaths.

Sans was immediately at their side. "Whoa, hey kiddo, are you alright?" Frisk let him help them stand, but made a dismissive gesture with their hand. "I'm fine." Sans didn't call out the obvious lie, since it'd be pretty hypocritical of him to do so, but he raised an accusatory brow-bone at them and refused to let go of their arm. They didn't even check the display board again as they walk by. Not that it would have mattered. It was blank. Silent. Smug.

It took too long for Sans to realize that the hallway hadn't always been this long last time he was down here. And wasn't there supposed to be a door somewhere along the wall? There wasn't one now, and the red backup lights definitely seemed liked they were getting dimmer. The walls were completely painted in the black ooze down the hallway. Of course, it still didn't touch the message boards they came across, making them look like they were floating on to of the thick stuff. The first board was broken, spiderwebbed across the glass screen and silent. The second was alive with waiting static, ready to display a new message once hey got close enough. Sans considered just walking by, completely ignoring their cryptic and totally bullshit "ally". Frisk, however, didn't share that idea.

Sans couldn't tell if they were gaining confidence or if it was all their determination powering them through, but Frisk didn't hesitate much at all before trotting over to the board and tapping the screen with their finger. "Hello?"

The display blinked bright and red, responding instantly: " 1001 !'M HERE, CH!LD. BE 001CAREFUL. SHE !S N0T THE PERS0NNN Y0U KNEW111"

"What?" Sans and Frisk said together, but the board went blank and stayed so. Sans's brow bone creased and he ran a frustrated hand over his skull. "Well great. Things just keep getting' weirder, huh, kid?" Frisk's nod conveyed a world of exhaustion.

They carried on down the hallway for much longer than they should have. It was like it'd been stretched, the black goo adding to its length. It had to have been another five minutes of walking before they saw the entryway to the next room and, from it, heard the fainest sigh. Frisk perked up and jerked forward, urging Sans to go faster. As they approached Sans could see the lights in the room shifting with someone casting shadows. He pulled the kid up just short of the entrance and folded his hand over their mouth, pressing the finger of his other hand over his own skeletal grin in a hushing gesture.

For a brief, horrifying moment, Sans only saw the machine, surrounded by blackness and lit with harsh angles by the red overhead lights. He thought that thing had been destroyed. It should have been destroyed! Infuriatingly, he couldn't remember exactly why it was such an abomination. All he knew is that it was. Metal curved into a vaguely skeletal shape, too much like his blasters, and hung ominous and threatening against the black-coated wall. Rust painted most of the machine a bloody burgundy, and the shadows in its curves were too dark, too solid, and wrong wrong wrong. But then he saw who stood beside it, running a clawed hand down one cruel metal curve, and he understood why it was here. Of course she'd rebuilt it. Sweet, fragile Alphys, who always felt she had something to prove.

Of course, it only took a glance for Sans to understand what their mysterious companion had meant. This wasn't Alphys. Not really. This monster, turned so that their profile was just barely angled towards them, looked like their timid friend, but her skin was ashy gray and her eyes were black and empty. She wore a lab coat, but the colors were inverted, with her dress beneath being white while the coat was black. The same too-black as the ichor on the walls and in the machine.

She froze, tilting her head to the side, still facing away from them, and clicked her claws against the metal of the machine. "You know," she said, voice flat and dull and vaguely sardonic, "skulking in the doorway is only wasting all of our time. You have places to be, and I have things to do. Come in already so we can get this over with. "

Frisk flinched beside him at not-Alphys's tone and Sans's grin drew down in a tense frown. With the kid's hand gripped tight in his, he moved into the room and planted himself a few feet away, shoving his free hand into his hoodie pocket and raising his chin in daring expectation. "Who the hell are you? Because I know Alphys, and it don't matter how much you look like her, because you ain't her."

With an irritated sigh, she turned to fully face them, and Frisk whimpered. Sans squeezed their hand in sympathy. It really was disturbing, how far off from Alphys this thing was, with her hallow expression and frown, the kind that looked permanently etched into a person's face.

"You're right, in a way. But you're also wrong. I am Alphys, but not the one you know. I'm all the stray parts of her that she left behind, that she wanted to forget. Her guilt, her pain, her self hatred. All the discarded scrap memories of Alphys, spliced with a bit of the Void magic to hold it all together. . .that's me. Just a remnant, really." She said, sounding bored, like she'd prepared these lines before hand and was just rattling off a dull script. "That's what just about all of us are, down here now. Just the echoes and shadows you all left behind to fade away."

Both Sans and Frisk stared at her, taken aback. "That's, uh, some pretty dark stuff, pal. But, if ya don't mind my asking, whats this about Void magic? And by 'all of us', you mean that there are others like you down here? Other, uh, remnants?"

She leaned back against the machine, its rusted metal giving a mournful groan, and began to idly scratch at her arm. " The Void is the nowhere place in between timelines. A dark, empty purgatory that exists alongside your own world. When the Underground went empty, a state it was not designed for, the Void reacted in an attempt to fill the emptiness. Or consume it, I suppose. The Void's sole inhabitant, your friend with the message boards, was able to influence this enough so that the Underground began assimilating, in its own form, with the Void, rather than disappearing. His actions resulted in what you see around you, and in the incidental formation of remnant beings such as myself. There are several others, existing with varying degrees of success throughout this place. It is not an easy task. Reality is a very loose term, now," she said, glancing down at her arm. It was only then that Sans noticed that the'd scratched through her scaly skin, and had three deep gauges in her arm.

"What the hell?" he snapped, rushing forward to pry her hand away from her wounded arm. Frisk whimpered and grabbed her hand gently, looking at the cuts. Sans's eyes narrowed at them. Instead of blood, the same black ichor from all around was spilling out of her arm.

She sighed and met his eyes, looking as if she was proving a point. "We aren't real," she said, and pulled her injured arm away from Frisk.

Quiet tears slipped down Frisk's cheek, and Sans put a hand on their shoulder in sympathy. Remnant Alphys- because really, what else was he supposed to call her?- turned around and started running her hand over the machine again, as if nothing was wrong with her arm at all. She tilted her head to the far end of the room and said, "There is a door over there which will take you to the beginning of the Ruins. Obviously, this place does not exactly follow the laws of physics, nor is it as linear as you may recall. Not everywhere you end up will be familiar, so be careful. If you want to get back to the Surface, you'll need to find the Man Who Speaks In Hands. He's the only one who can clear the errors so you can get through the gate. Good luck."

It was a dismissal, but Sans still had a dozen and a half questions he wanted answered. Like, who was this Man Who Speaks In Hands, and why use the message boards instead of just showing up? Why'd he manipulate the Void's consumption of the Underground this way? What was really up with these Remnants, and who else would they find? Where was the damn flower?

How long until he and Frisk could see the sun again?

He didn't ask though, since Frisk, still silently sobbing, dragged him away from her and towards the door she had indicated. There was inky black on their hand, and they were trembling. Sans squeezed their digits in his. No matter what, he'd get them both home. He was determined.


End file.
